SCSI Bus

MegaRAID Express 500 has a Fast and Wide Ultra 160M SCSI channel that supports both LVD and single-ended devices with active termination. Synchronous and asynchronous devices are supported. MegaRAID Express 500 provides automatic termination disable via cable detection. The SCSI channel supports up to 15 wide or seven non-wide SCSI devices at speeds up to

160 MB/s. MegaRAID Express 500 supports up to six non-disk devices per controller.

SCSI Connectors

MegaRAID Express 500 has two types of SCSI connectors:

•a 68-pin high density internal connector

•a 68-pin external ultra-high-density connector

Both connector types can be used for the SCSI channel.

SCSI Termination

MegaRAID Express 500 uses active termination on the SCSI bus conforming to Alternative 2 of the SCSI-2 specifications. Termination enable/disable is automatic through cable detection.

SCSI Firmware

The MegaRAID Express 500 firmware handles all RAID and SCSI command processing and also supports:

Feature

Description

 

Disconnect/

Optimizes SCSI Bus seek.

 

Reconnect

 

 

Tagged Command

Multiple tags to improve random access

 

Queuing

 

 

Scatter/Gather

Multiple address/count pairs

 

Multi-threading

Up to 255 simultaneous commands with elevator sorting and

 

 

 

concatenation of requests per SCSI channel

 

Stripe Size

Variable for all logical drives: 2 KB, 4 KB, 8 KB, 16 KB, 32

 

 

 

KB, 64 KB, or 128 KB.

 

Rebuild

Multiple rebuilds and consistency checks with user-

 

 

 

definable priority.

 

 

 

 

 

34MegaRAID Express 500 Hardware Guide